Crypto Realtime

Simple demo app that shows realtime cryptocurrency prices using Socket.IO and CoinGecko.

Quick start

1. Install dependencies

npm install

2. Start server

npm start

3. Open http://localhost:3000

Notes

• If you have a CoinGecko PRO API key, set it in an environment variable named COINGECKO_API_KEY (or create a .env file with that variable) — the server will automatically send it using the x-cg-pro-api-key header.- To set it easily on your machine without editing files, run: Prices are polled every 10 seconds from the free CoinGecko API. Modify server/index.js to change coin list or interval. If you have a CoinGecko PRO API key, set it in an environment variable named COINGECKO_API_KEY (or create a .env file with that variable) — the server will automatically send it using the x-cg-pro-api-key header.
• To set it easily on your machine without editing files, run:

npm run set-key -- YOUR_API_KEY_HERE

This will write a local .env (ignored by git). Do NOT paste your API key into source files or commit it to version control.

• Polling/backoff: the server polls CoinGecko and will automatically back off if it receives HTTP 429 (rate limit). You can change default timing with

export POLL_INTERVAL_MS=10000
export MAX_POLL_INTERVAL_MS=120000